How can I help an elderly man up safely?

I called our 311 number for non emergency assistance. A big fire truck showed up with four big and strong firemen on it. They were very good and two of them helped her back into bed.
She had slipped out by accident.
I helped once and both of us wound up with injuries, mild but injuries non the less.
Most cities that I know of will dispatch assistance. She was not injured and no medical was require. Now I tease her about just wanting to meet those cute guys and we both laugh. I do the same thing when she wants to go to the Air Force Exchange. I tease her about wanting to meet a helicopter pilot to take her out for a ride.
I am 70 and she is 74.
You might check with your doctor or a rehab facility and try to arrange a lesson on how to assist. I think there are some online videos that may help.

I agree call 911. My daughter was trained in how to do this but the patient moved on her and her back paid the price. If they can't help you then don't try it. They r dead weight. Does this person live with you? If so, it maybe time for long term care.

If he is able to use a chair to get up, then coach him to crawl to the chair, then get on one knee to push himself up. If he isn't able to do that, then calling 911 is a very good idea.

This is just my opinion, but I would call 911,and have when hubby has collapsed. One crew was wonderful and caring. The other crew that came out...not so much, but they did help get him off the floor. Nurse’s aides and other patient care personnel go to school to learn how to properly and safely pick people up off the floor. I speak from experience. I dislocated my shoulder trying to get hubby up.

If this person falls regularly, I’d call his doctor and see if something can be done—wheelchair, bed rails, etc.

Here's an article that give some help hints: https://www.agingcare.com/articles/pick-up-a-senior-after-a-fall-170447.htm